Interlocking, Full-Circumference Packer Slip

ABSTRACT

A packer assembly constructed of individual slip segments which interlock to permit radial expansion and restrict axial movement. The slip segments are moved outwardly to set the packer by an actuator. Individual slip segments are easily and inexpensively manufactured.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) to PCT Application Serial No. PCT/US2014/056441 entitled, “ INTERLOCKING, FULL-CIRCUMFERENCE PACKER SLIP,” which was filed on Sep. 19, 2014, and is hereby incorporated by reference in its entirety.

BACKGROUND

Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore is drilled, various forms of well completion components may be installed in order to control and enhance the efficiency of producing the various fluids from the reservoir. One piece of equipment which may be installed is a packer to provide mechanical support to other downhole components by engaging walls of the well or a casing in the well. Packers use slips to physically engage the interior surface of the well.

SUMMARY

The present disclosure is directed to a slip assembly for a packer, including one or more slip segments arranged around a mandrel. Individual sip segments have a first end and a second end. The first end has an interlocking feature which permits the slip segments to expand radially outwardly from the mandrel when actuated and which restricts axial movement of the slip segments when actuated. The slip assembly also includes an actuator configured to actuate the slip assembly by moving the slip segments radially outwardly.

The slip segments can be alternatingly inverted. The interlocking features permit the slip segments to move radially relative to the mandrel and inhibit the first and second slip segments from moving relative to one another axially. In other embodiments the interlocking feature comprises an H-shaped feature configured to restrict axial movement of the slip segment in two opposite axial directions.

Other embodiments of the present disclosure are directed to a packer including a mandrel and an actuator coupled to the mandrel and configured to actuate in response to a signal to set the packer, and slip segments having an interlocking feature at a first end and a setting surface at a second end opposite the first end. Adjacent slip segments are inverted such that the interlocking feature of each slip segment engages the interlocking features of two adjacent, inverted slip segments. The interlocking features restrict axial movement and permit radial movement, and the actuator causes the slip segments to move radially relative to one another to set the packer.

In still further embodiments the present disclosure is directed to a method of actuating a packer, including running the packer to a desired location in a downhole well, and actuating a setting mechanism to expand a slip assembly. The slip assembly includes a plurality of slip segments that move radially outwardly to engage a surface of the well and to restrict axial movement of the slip segments.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of packers and slip assemblies are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components. It is emphasized that, in accordance with standard practice in the industry, various features are not necessarily drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is an isometric view of a packer assembly according to embodiments of the present disclosure.

FIG. 2 illustrates an individual slip segment of the packer assembly of FIG. 1 according to embodiments of the present disclosure.

FIG. 3 is a cross-sectional view of a packer assembly according to embodiments of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

FIG. 1 is an isometric view of a packer assembly 100 according to embodiments of the present disclosure. The packer assembly 100 is generally cylindrical and sized to fit within an oil well. The slip assembly 100 is coupled to a mandrel 102, which can be production tubing, or any other suitable downhole equipment to support a packer. The packer assembly 100 includes an actuator 104, and several slip segments 106 arranged circumferentially around the packer assembly 100. The packer assembly 100 also includes garter springs 108 encircling the slip segments 106 to hold them in place until actuated. When actuated, the slip segments 106 are moved radially outwardly by the actuator 104 to engage a casing or an open well to set the packer. The slip segments 106 have an interlocking feature 110 that permits the slip segments 106 to move radially and restricts them from moving axially. The slip segments 106 are discrete pieces, allowing the assembly 100 to expand without deforming individual elements. Spacers, or keys, can be placed between slip segments 106 circumferentially to achieve desired circumferential spacing. A spacer can be placed between each pair of slip segments, or every three segments, etc.

FIG. 2 illustrates an individual slip segment 106. The slip segment 106 includes a setting surface 120 having teeth 122 or other textured features. The slip segment 106 also includes an interlocking feature 110 having a shoulder 124, a neck 126, and a tab 128. The neck 126 is narrower than the shoulder 124; the shoulder 124 is narrower than the tab 128. The interlocking feature 110 accordingly has an H-shape with the neck 126 being the intermediate portion of the H. The interlocking shape allows adjacent slip segments 106 having a similar shape to interlock to permit radial expansion and contraction, but that restricts axial relative movement. Circumferential movement is also permitted to some degree, at least because the radius is larger when expanded than when contracted. The slip segment 106 includes grooves 130 to accommodate the garter springs 108, and a hole 132 to accommodate a shear screw (not shown). The shear screw can hold the slip segments 106 in place during run in hole.

The slip segments 106 are curved and together make up a substantially complete circumference of the packer assembly 100. The sides of the slip segments 106 are generally flat and radially aligned to approximate a continuous slip barrel, and the outer and inner faces are curved to match the shape of the mandrel 102 and the casing or well (not shown) against which the packer is set. This construction allows the packer assembly 100 to set and expand without deforming the slips, therefore actuation requires comparatively less energy than other designs which rely on flexible slips or slips with flexible portions. In addition, the packer assembly 100 is more easily retrieved because the slips do not deform. In other words, the process of setting the packer assembly 100 is more easily reversed than with previous designs.

Eliminating the need for deformable slips allows the slip segments 106 to be made from a broader range of materials not limited to those with high ductility, and permits a broader range of hardening processes not limited to those that may compromise the ductility. Furthermore, the individual slips segments 106 are comparatively less expensive to manufacture due to their small size relative to the packer assembly 100 as a whole, and can be made using less expensive manufacturing techniques such as casting. For example slip segments 106 may be carburized to improve durability and reliability.

FIG. 3 illustrates a diametrical cross section of the packer assembly 100 of FIG. 1. The slip segments 106 are in a collapsed state around the mandrel 102. The assembly 100 includes an actuator which, in some embodiments, comprises one or more cone portions 140, 142. In the depicted embodiment there are two opposing cone portions 140, 142 which have outwardly-facing ramp portions that compliment ramp portions of the slip segments. When the cone portions 140, 142 are moved toward one another (either by moving one or the other or both of the cone portions 140, 142) the ramp portions cause the slip segments 106 to move radially outwardly from the mandrel 102 with the interlocking features 110 of the slip segments 106 permitting radial movement, but restricting axial movement. The slip segments 106 contact an outer wall and set the packer. In some embodiments one cone portion 140 can be actuated first, causing the slip segments 106 contacting it to expand first, and the second cone portion 142 is actuated second causing similar movement of the other slip segments 106, or vice versa.

As used herein, the terms “connect,” “connection,” “connected,” “in connection with,” and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element”. Further, the terms “couple,” “coupling,” “coupled,” “coupled together,” and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms “up” and “down”; “upper” and “lower”; “top” and “bottom”; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point as the surface from which drilling operations are initiated as being the top point and the total depth being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface. 

What is claimed is:
 1. A slip assembly for a packer, comprising: one or more slip segments arranged around a mandrel, the individual slip segments having a first end and a second end, the first end having an interlocking feature which permits the slip segments to expand radially outwardly from the mandrel when actuated and which restricts axial movement of the slip segments when actuated; and an actuator configured to actuate the slip assembly by moving the slip segments radially outwardly.
 2. The slip assembly of claim 1 wherein the interlocking feature comprises an H-shaped feature configured to restrict axial movement of the slip segment in two opposite axial directions.
 3. The slip assembly of claim 1 wherein the slip segments are first slip segments, the slip assembly further comprising second slip segments, the second slip segments having a cooperating interlocking feature, wherein the second slip segments are inverted relative to the first slip segments, and wherein the interlocking features permit the slip segments to move radially relative to the mandrel and inhibit the first and second slip segments from moving relative to one another axially.
 4. The slip assembly of claim 1 wherein the slip segments have a ramped portion facing inward toward the mandrel, and wherein the actuator comprises a corresponding ramp portion configured to move axially against the ramp portion of the slip segments to cause the slip segments to move radially outwardly.
 5. The slip assembly of claim 1 wherein the interlocking feature permits the slip segments to move circumferentially away from one another when actuated.
 6. The slip assembly of claim 1 wherein the slip segments have an outwardly-facing setting surface having a non-uniform circumferential profile.
 7. The slip assembly of claim 6 wherein the non-uniform circumferential profile comprises a herringbone pattern.
 8. The slip assembly of claim 6 wherein the non-uniform circumferential profile comprises parallel slots cut in two or more directions to produce teeth on the profile.
 9. The slip assembly of claim 6 wherein the non-uniform circumferential profile comprises semi-circular indentations protruding from the outwardly-facing setting surface.
 10. The slip assembly of claim 1 wherein the slip segments have two or more ramped portions facing inward toward the mandrel, and wherein the actuator has corresponding ramped portions engaging the ramped portions of the slip segments.
 11. The slip assembly of claim 1, further comprising garter springs encircling the slip segments.
 12. The slip assembly of claim 1 wherein the interlocking feature comprises a shoulder, a neck extending from the shoulder, and a tab extending from the neck, wherein the neck is narrower than the shoulder, and wherein the tab is wider than the neck.
 13. The slip assembly of claim 1, further comprising a shear screw in the slip segments configured to hold the slips in place relative to the mandrel until actuated, at which point the shear screw will shear and permit the slip segments to move relative to the mandrel.
 14. The slip assembly of claim 1 wherein the slip segments are cast.
 15. The slip assembly of claim 1 wherein the slip segments are carburized.
 16. The slip assembly of claim 1 wherein the slip segments are curved to generally match the mandrel, and wherein the sides of the slip segments face adjacent slip segments and are generally flat and parallel with a radius of the slip assembly.
 17. The slip assembly of claim 1, further comprising one or more keys interspersed around the circumference to limit circumferential movement of the slip segments.
 18. A packer, comprising: a mandrel; an actuator coupled to the mandrel and configured to actuate in response to a predetermined condition to set the packer; slip segments having an interlocking feature at a first end and a setting surface at a second end opposite the first end, wherein adjacent slip segments are inverted such that the interlocking feature of each slip segment engages the interlocking features of two adjacent, inverted slip segments, wherein the interlocking features restrict axial movement and permit radial movement, and wherein the actuator causes the slip segments to move radially relative to one another to set the packer.
 19. The packer of claim 18 wherein the slip segments are not deformed by the actuator.
 20. A method of actuating a packer, comprising: running the packer to a desired location in a downhole well; actuating a setting mechanism to expand a slip assembly, wherein the slip assembly comprises a plurality of slip segments configured to move radially outwardly to engage a surface of the well and to restrict axial movement of the slip segments.
 21. The method of claim 20 wherein actuating the setting mechanism does not deform the individual slip segments.
 22. The method of claim 20 wherein actuating the setting mechanism comprises sliding slip segments relative to one another. 